Telephone-transmitter



(No Model.)

v W. A. MASON. TELEPHONE TRANSMITTER.

No. 532,979. Patented Jan. 22 1895.

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" NITED STATES- PATENT ()FFICE.

WILLIAM A. MASON, OF SUMTER, SOUTH CAROLINA.

TELEPHONE-TRANSMITTER.

SP ECIFICATION forming part of Letters Patent No. 532,979, dated January22, 1895. Application filed October 26, 1894- Serial No. 527,030- (Nomodel.)

South Carolina, have inventedanew and useful Improvement inTelephone-Transmitters, of which the following is a specification.

My invention is an improvement upon that form of telephone transmitterin which one or more carbon pencils or bars hangs or leans from gravityagainst another carbon bar or pencil, the latter being attached to thevibrating diaphragm and forming one terminal of the circuit, while thegravitating pencils or bars form the other.

My improvement consists in constructing the gravitating or leaning barswith a hole through the same through which passes the other carbonelectrode, and also in reaming out this hole on both sides so as to forma sharp circumferential edge at the point of contact whereby an extremesensitiveness for low tones is obtained, without any jarring orconfusion of sounds in the louder tones.

Figure 1 is a front view partly in section; Fig. 2, a side view partlyin section of the electrodes of my improved transmitter, and Figs. 3 and4 are enlarged details of the contact points of the electrodes,illustrating the difference between my contacts in Fig. 3, and an oldform shown in Fig. 4.

In the drawings, A represents a series of parallel carbon bars orpencils, each independently and loosely hung upon a hollow metal tube Bwhich, with said carbon bars or pencils, form one terminal of thetalking circuit of the transmitter. The lower ends of these bars areprovided with a circular hole 6 entirely through the same, which hole isreamed out or tapered upon each side, as at a a, so as to leave a sharpcircumferential wedge shaped edge for the hole in the center of each barwhich forms a bearing edge for said bar against the other-electrode. Gis the other electrode, which is a round carbon pencil arranged inhorizontal position, fixed to the diaphragm D, and passing through allthe holes I) of the series of gravitating carbon bars A. These bars arearranged in an inclined position so as to lean lightly on one side ofthe holes 12 against the horizontal carbon pencil, the holes in thebarsA beingjust a trifle larger than the carbon electrode 0 which passesthrough them.

When the diaphragm'and carbon electrode C are set to vibrating by theact of talking, the contact between said electrode and one side of thesharp circumferential edge of the gravitating' bars produces thevariable resistance between the electrodes that give great efiectivenessin the transmission of the electric impulses and the reproduction of thetones of the voice through the other dia phragm, the sharpened edgeserving to give great sensitiveness and clearness to all low tones,without involving any jar or confusion in the reproduction of the loudertones. The fiat sidesand closely adjacent position of the sides of thebars also keeps them in true parallel position, so that one bar has notendency to ride upon or wedge against the next adjacent one.

By passing one electrode 0 through an opening in the bars A, the latterare all held in place without any encompassing yoke or external frame,so that the bars can never fall away from their true position, while thehollow 'm'etal suspending tube B permits of a very light constructionand a perfect connection between the circuit wire and the gravitatingbars A.

Another important distinction and function involved in the extension ofone electrode through a hole in the other is as follows: Thecircularconvex surface of the electrode 0 makes cootact'with thecircular concave surface of the bars, which two curves are very nearlyof the same radius, and as the convex surface vibrates against theconcave surface in a line Z Z, Fig. 3, radial to the two curves, itbrings into variable contact without any sliding friction a much largersurface, and a much quicker departure of these surfaces than where acarbon pencil simply rests tangentially upon'the exterior of a convexsurface. Thus in Fig. 4 which shows an old arrangement, the tangentialarrangement of one of the straight electrodes on the curved surface ofthe other electrode makes a contact at practically a single point onlyon the convex periphery, while with my arrangement, shown in Fig. 3, thecontact between the two curved surfaces is much greater because thecurves of the two circles are nearly coincident, and the sensitivenessof the variable contact is much greater.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is l 1. In a telephone transmitter, thecombination of one or more loosely leaning or gravitating carbon bars orpencils having at their free ends an opening entirely through them; of acarbon electrode passing through said openings in the gravitating barsand serving the double function of making a vibrating electricalcontact, and holding in place the gravitating bars, substantially as andfor the purpose described.

2. In a telephone transmitter, the combina tion of one or more looselyleaning or gravitating carbon bars or pencils having at their free endsan opening through them countersunk to form a sharp circumferentialbearing edge, and a carbon electrode passing through said opening andmaking vibratory contact with said edge substantially as and for thepurpose described.

3. In a telephone transmitter, the combination of a series of looselyleaning or gravitating carbon bars having fiat sides adjacent to eachother and an opening through their free ends, and a carbon electrodepassing through said opening, substantially as and for the purposedescribed.

WILLIAM A. MASON.

Witnesses:

W. B. PEEBLEs, F. G. BEHRE.

